The authors would like to thank the companies for the access of their monofocal and multifocal IOLs. This work was supported by Oak Ridge Institute for Science and Education (ORISE) and the Medical Device Fellowship Program (MDFP) and their contributions are appreciated. In addition, the authors would like to thank Samuel Song for his contributions in the laboratory.

1. SLSP Measurement Platform Preparation
NOTE: All alignment steps require precision and patience to ensure accurate quantitation when measuring light scatter. An overview of the SLSP setup in provided within Figure 1. Here, an illustration (Figure 1a) shows the basic concept of the SLSP setup. In addition, Figures 1b and 1c help define the various angles referenced within the discussion. Specifically, the following three angles are defined within Figures 1b and 1c: &#730;R (sensor rotational angle), &#730;S (sensor angle of measurement), and &#730;I (IOL angle of incidence).
<ol>
	<li>SLSP Alignment (Figure 2).
	<ol>
		<li>Focus a narrow-linewidth laser source (here, a 543 nm central wavelength) into a single-mode delivery optical fiber using a 10&#215; infinity corrected objective lens. 
		NOTE: Test the light source to ensure that the lumen output is steady or measurements will be difficult to quantify. A focused beam is determined by observing light passing through the fiber, this will not achieve 100% efficiency, but should be enough so that light can ultimately be detected by the sensor.</li>
		<li>Collimate the light source by integrating the single-mode optical fiber with a 10X infinity corrected objective lens so that the fiber is positioned on the focal point of the objective lens. The output light should result in a uniform Gaussian beam profile.</li>
		<li>Position an iris aperture in front of light source to adjust the diameter of Gaussian beam. 
		NOTE: Set the iris aperture diameter to be representative of a human eye (e.g. 1-6 mm diameter). As the light scatter type complaints are commonly associated with night driving, iris aperture diameters representative of a dilated iris may be preferable.</li>
		<li>Construct a goniophotometer by attaching a photodiode sensor to a motorized/programmable 360&#730; rotational stage with linear translation (x, y, and z direction) capabilities using an extendable arm (metal post with post clamp). 
		NOTE: Design a stage platform that enables translation as well as tilt adjustments. Design the sensor mount that enables 360&#730; of sensor rotational angle (&#730;R) and can be adjusted to at least 45&#730; of sensor angle rotation (&#730;S) to measure different planes of scatter. The distance of the extended arm is dependent on the sensitivity of the photodiode sensor and the desired angular precision.</li>
		<li>Adjust the sensor angle of detection (as needed) by angling the sensor face and adjusting the location of the arms.</li>
	</ol>
	</li>
	<li>IOL Alignment
	<ol>
		<li>Construct an IOL holding platform so that the IOL is positioned above the goniophotometer (Figure 2).
		<ol>
			<li>To accomplish this, build the IOL holding platform so that the IOL is suspended above the center of the goniophotometer (reversing the positions of the goniophotometer and IOL is also possible).
			<ol>
				<li>To construct the platform use four, 18&#34; long, &#189;&#34; diameter cylindrical posts and post stands and attach them to a 18 x 18&#34; breadboard. This breadboard is the base support for the platform.</li>
			</ol>
			</li>
		</ol>
		</li>
		<li>Attach a translational stage (x, y, and z direction) with tilting and rotational (I&#730;) capabilities underneath the breadboard so that the stage is facing down. 
		NOTE: Translation stages with small step sizes (a few microns) enable higher precision during the alignment of the IOL and will improve goniophotometry accuracy. The specific dimensions of the platform can be customized to individual needs. As a result, the cylindrical posts and breadboard dimensions can be adjusted.
		<ol>
			<li>Securely attach the IOL to the IOL holding platform by clamping one of the IOL haptics. 
			NOTE: In this proof of purpose experiment, IOLs are tested in air; however, IOLs in solution and temperatures that best represent in vivo conditions would be ideal.</li>
		</ol>
		</li>
		<li>Align the IOL directly in front of the light source (with the IOL plane of focus perpendicular to the light source) using linear and tilt adjustments from the IOL holding platform stage to ensure that the direction of light does not change while passing through the center of the IOL. This position will constitute an angle of incidence (I&#730;) of 0&#730;.</li>
		<li>Identify the location of the focal spot of light from the IOL and position a small conical device at the focal spot to mitigate detection of defocused light (when necessary). Identify the focal spot of light by placing a piece of paper (such as a business card) behind the IOL and identifying where the light is most tightly focused. This can be a subjective measurement. 
		NOTE: This step is only necessary if wanting to measure purely non-ballistic light.</li>
		<li>Position the motorized stage for the photodiode sensor directly underneath the IOL to ensure that the IOL is located in the center of the goniophotometer trajectory. Align the goniophotometer so that it is approximately 12 cm away from the IOL. 
		NOTE: The relationship of the IOL and the goniophotometer will determine the resolution of the tests, where the further away the goniophotometer is located the greater resolution can be achieved. However, increased distance (and smaller step sizes) will result in lower signal and longer experimentation times.</li>
		<li>Adjust the angle of incidence (I&#730;) by rotating the IOL holding platform stage. 
		NOTE: Initial experiments should be conducted with an angle of incidence of 0&#730; to 80&#730;. Beyond 80&#730; will begin to near the grazing angle where all light will be reflected.</li>
	</ol>
	</li>
	<li>Programming
	<ol>
		<li>Build a software program to coordinate the mechanical movement of the sensor with its corresponding light measurement using system design software (see Supplemental file 1 and Table of Materials). 
		NOTE: When building the software program take into consideration the speed of the sensor to ensure that the physical location of the sensor accurately reflects its recorded measurement. The program designed for this experiment is provided in Supplemental file 1.</li>
	</ol>
	</li>
</ol>
2. SLSP Experimentation and Data Analysis
<ol>
	<li>Scanning (&#730;R)
	<ol>
		<li>Ensure that the IOL and the light source are properly aligned (see sections 1.1 and 1.2).</li>
		<li>Construct an enclosure around the photodiode sensor and the IOL using a container with non-reflective internal coating to minimize the detection of errant light. Ensure to provide an opening for the light source. 
		NOTE: The specific design of the enclosure should be customized based on an external light in the room. As a result, multiple designs are usable. However, the purpose of the enclosure is to mitigate all external light from being detected by the sensor.</li>
		<li>Turn off all light sources within the room, except for the programming computer.</li>
		<li>Run the SLSP software program (step 1.3.1) so that the sensor rotates around the IOL to measure scattered light at each degree of rotation (&#730;R).</li>
		<li>To measure scattered light at more than one plane, run the SLSP software program multiple times while manually adjusting the sensor&#39;s extended arm and sensor angle of measurement (&#730;S). 
		NOTE: The number of times the program is run is dependent on the desired outcome. The more angles of detection measured will result in more precision for identifying the directionality of scattered light.</li>
		<li>For studies on beam diameter, adjust the iris aperture to the desired diameter before running the SLSP program. 
		NOTE: Here, the laser beam diameters of 1, 2, 3, 4, and 4.64 mm were used to best mimic typical iris diameters. 4.64 mm was the largest diameter used as this was the diameter of the collimated beam without passing through the iris aperture.</li>
		<li>For studies on angle of incidence, rotate the IOL mount to the desired angle of incidence before running the SLSP program. Here, angles of incidence (I&#730;) of 0&#730;, 20&#730;, 45&#730;, and 80&#730; were studied. 
		NOTE: A scientific data processing package is needed for the analysis of the collected data.</li>
		<li>For three dimensional imaging, stich together the data from each scan at differing &#730;S with a data processing package. Stich the data by plotting a matrix book where the sensor angle of measurement (&#730;S) is plotted against the angle or rotation (&#730;R). 
		NOTE: To better represent in vitro conditions, the SLSP platform can be reversed so that the goniophotometer is above the IOL and the IOL can then be placed inside of a temperature controlled saline solution bath. However, in these conditions, sensor dwell times will need to be considerably longer to take into consideration the motion of the saline solution as the sensor is moved from position to position and displaces the medium.</li>
	</ol>
	</li>
</ol>

<ol>
	<li>Walker, B. N., James, R. H., Calogero, D., Ilev, I. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+full-angle+scanning+light+scattering+profiler+to+quantitatively+evaluate+forward+and+backward+light+scattering+from+intraocular+lenses.">A novel full-angle scanning light scattering profiler to quantitatively evaluate forward and backward light scattering from intraocular lenses.</a> Rev. Sci. Instrum. 86 (9), (2015).</li><li>Vandenberg, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=On+the+relation+between+glare+and+straylight.">On the relation between glare and straylight.</a> Doc. Ophthalmol. 78 (3-4), 177-181 (1991).</li><li>De Hoog, E., Doraiswamy, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+the+impact+of+light+scatter+from+glistenings+in+pseudophakic+eyes.">Evaluation of the impact of light scatter from glistenings in pseudophakic eyes.</a> J. Cataract. Refract. Surg. 40 (1), 95-103 (2014).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Global Intraocular Lens Market 2013-18: Industry Nanotechnology Analysis, Size, Share, Strategies, Growth, Trends and Forecast Research Report. , (2013).</li><li>Congdon, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prevalence+of+cataract+and+pseudophakia/aphakia+among+adults+in+the+United+States.">Prevalence of cataract and pseudophakia/aphakia among adults in the United States.</a> Arch. Ophthalmol. 122 (4), 487-494 (2004).</li><li>Mester, U., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impact+of+Personality+Characteristics+on+Patient+Satisfaction+After+Multifocal+Intraocular+Lens+Implantation:+Results+From+the+&amp;#34;Happy+Patient+Study&amp;#34.">Impact of Personality Characteristics on Patient Satisfaction After Multifocal Intraocular Lens Implantation: Results From the &amp;#34;Happy Patient Study&amp;#34.</a> J. Refractive Surg. 30 (10), 674-678 (2014).</li><li>Ferrer-Blasco, T., Montes-Mico, R., Cervino, A., Alfonso, J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Light+Scatter+and+Disability+Glare+After+Intraocular+Lens+Implantation.">Light Scatter and Disability Glare After Intraocular Lens Implantation.</a> Arch. Ophthalmol. 127 (4), 576-577 (2009).</li><li>Landry, R. J., Ilev, I. K., Pfefer, T. J., Wolffe, M., Alpar, J. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterizing+reflections+from+intraocular+lens+implants.">Characterizing reflections from intraocular lens implants.</a> Eye. 21 (8), 1083-1086 (2007).</li><li>Kim, D. H., James, R. H., Landry, R. J., Calogero, D., Anderson, J., Ilev, I. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantification+of+glistenings+in+intraocular+lenses+using+a+ballistic-photon+removing+integrating-sphere+method.">Quantification of glistenings in intraocular lenses using a ballistic-photon removing integrating-sphere method.</a> Appl. Opt. 50 (35), 6461-6467 (2011).</li><li>Portney, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=IOL+with+Square-Edged+Optic+and+Reduced+Dysphotopsia.">IOL with Square-Edged Optic and Reduced Dysphotopsia.</a> Optom. Vis. Sci. 89 (2), 229-233 (2012).</li><li>Choi, J., Schwiegerling, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+performance+measurement+and+night+driving+simulation+of+ReSTOR,+ReZoom,+and+Tecnis+multifocal+intraocular+lenses+in+a+model+eye.">Optical performance measurement and night driving simulation of ReSTOR, ReZoom, and Tecnis multifocal intraocular lenses in a model eye.</a> J. Refractive Surg. 24 (3), 218-222 (2008).</li><li>Artigas, J. M., Felipe, A., Navea, A., Carmen Garcia-Domene, M., Pons, A., Mataix, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+scattering+in+intraocular+lenses+by+spectrophotometric+measurements.">Determination of scattering in intraocular lenses by spectrophotometric measurements.</a> J. Biomed. Opt. 19 (12), (2014).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ophthalmic+implants+-+Intraocular+lenses+Part+2:+Optical+properties+and+test+methods.">Ophthalmic implants - Intraocular lenses Part 2: Optical properties and test methods.</a> The International Organization for Standardization (ISO). ISO 11979 (2), (2014).</li></ol>

The mention of commercial products, their sources, or their use in connection with material reported herein is not to be construed as either an actual or implied endorsement of such products by the Department of Health and Human Services.

The results from the SLSP platform experiments have found that using simple goniophotometry principles can lead to a powerful tool for evaluating the properties of light scatter associated with unique IOL designs and materials. Specifically, the SLSP platform has observed a direct correlation between the amount of detectable scattered light and the beam diameter of the light source. In addition, the multiple scattered peaks found in multifocal IOLs were easily observed with the SLSP. Furthermore, as the source of light a...

The scanning light scattering profiler (SLSP) approach was first introduced to address the need to quantitatively evaluate light scattering characteristics of intraocular lenses (IOLs) in a non-clinical setting1. Developing a test methodology to evaluate the light scattering tendencies of IOL designs and materials is of significant interest in order to help identify potential unwanted light scattering problems. Light scatter is commonly reported by patients and observed as glare, glistening, optical imperfections, and other forms of dysphotopsia2, sometimes leading to a patient requesting the IOL explantation. In addition to dysphotopsia, scattered light reduces the amount of ballistic light, resulting in lower overall image quality3. Developing a device that can non-clinically evaluate the IOL potential to scatter the incoming light (and later correlated with clinically reported outcomes) can be useful.
Evaluating optical properties of IOLs (the lens used to replace the human crystalline lens after cataract surgery) is of particular interest as it is the most commonly implanted medical device in the world (almost 20 million per year)4 and the United States (over 3 million per year)5. As a result, even a small percentage of patients reporting dysphotopsia may have a large impact. In addition, rapidly improving technologies (e.g. new IOL designs, materials, and optical capabilities) have the potential to increase concerns related to light scattering. For example, multifocal IOLs have been designed to improve near and far visual acuity by designing lenses that utilize refraction and diffraction optical principles. Although highly successful, these lenses have also been found to increase the amount of reported halos and glare, largely associated with scattering of light6.
A few non-clinical laboratory studies attempt to predict dysphotopsia from scattered light as it passes through IOLs7. For example, research has identified that IOL haptics (the arms of the IOL used to set it in place) and the edge of the IOLs are prone to induce a large amount of the observed glare scattered light8. One method, a ballistic-photon removing integrating-sphere method (BRIM), was introduced to quantitatively measure the amount of total non-ballistic light after passing through an IOL9. However, this highly sensitive technique is designed to measure the total intensity of scattered light and is unable to identify directionality of the scattered light. Computer simulation software can be used with model eyes to help predict intensity and directionality of light scatter from various IOL designs and materials. For example, the propensity for the IOL edge to induce the light scattering was simulated to identify designs that would limit the amount of scattered light10. Furthermore, computer simulations that incorporated the Mie scattering theory verified that increased light scatter can reduce the modulation transfer function (MTF) of the IOL (a direct correlation to image quality)3. Although helpful, real bench tests would be necessary to verify these predictive simulations.
To verify predictive simulations a bench test is necessary that is capable of detecting and quantitatively evaluating two distinct forms of scattered light, forward scattered and backward scattered light. Although not a source of dysphotopsia, backward scattered light (light scattering away from the eye) is a cause for reduced image quality, as less light passes through the IOL to ultimately reach the retina. Forward scattered light (light scattering towards the retina) is a concern for ophthalmologists as it may result in complaints of dysphotopsia (e.g. glare, halo, and glistening). One common example is patients reporting additional unwanted glare from passing oncoming cars during night driving; this issue is particularly common with multifocal IOLs11. However, current practice to identify potential forward scattered light is for ophthalmologists to shine light onto the patient&#39;s eye and qualitatively observe how much light is reflected back (backward scattered light) and assuming that the backward scattered light will be approximately the same as the forward scattered light (which is not always the case)12.
Here, we describe a simple test methodology using goniophotometry principles to quantitatively measure the magnitude and direction of scattered light at it passes through an intraocular lens. The SLSP operates by rotating a photodiode sensor 360 degrees around an IOL that is exposed to a light source, see Figure 1a. We chose a green laser source (543 nm) to best represent the known photopic maximum and to agree with the international standard specifications13. Here, an IOL is adapted onto a rotational and translational holder where a photodiode sensor can circle around and observe light scattering off of the lens. As a result, the SLSP has the unique capability to quantitatively measurement the magnitude and directionality of scattered light. However, although not described here, for better predictive capabilities, experiments should be conducted within a controlled environment using an appropriate eye model. The distance between the IOL and the optical sensor (as well as the size of the sensor element) will determine the resolution capabilities of the device; however, there will be a tradeoff between resolution and signal strength that will need to be adjusted, as needed.
To accurately describe the principles of the SLSP platform we define three types of rotational angles, see Figures 1b and 1c. Specifically, the rotation angle (&#730;R) represents the rotation of a photodiode sensor as it rotates around an IOL. Here, 0&#730;R would represent when the sensor is behind the lens (backward scattered light) and 180&#730;R represents when the sensor is in front of the lens (forward scattered light). Angles of 90&#730; and 270&#730; represent the transition points between forward and backward scattered light. The sensing angle (&#730;S) represents degrees that the sensor is pivoted (in the up and down direction) so that it can detect more than one plane of scattered light. Here, 0&#730;S means the sensor surface is parallel to the IOL (and light source). Finally, the angle of incidence (&#730;I) represents the angle that the light source is approaching the IOL from. Here, 0&#730;I corresponds to when the incident light is on the optical axis of the IOL and 90&#730; would represent when the light source is perpendicular to the Meridional plane.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>PD300 series Photodiode Sensor</td>
			<td>Ophir-Spiricon Corp</td>
			<td>7Z02410</td>
			<td>PD300-1W, RoHS</td>
		</tr>
		<tr>
			<td>URS Series Precision Rotation Stage</td>
			<td>Newport Corp.</td>
			<td>URS75BCC</td>
			<td></td>
		</tr>
		<tr>
			<td>ESP301 1-Axis Motion Controller and Driver</td>
			<td>Newport Corp.</td>
			<td>ESP301-1N</td>
			<td></td>
		</tr>
		<tr>
			<td>LabView Software</td>
			<td>National Instruments Corp.</td>
			<td>776671-35</td>
			<td></td>
		</tr>
		<tr>
			<td>Origin</td>
			<td>OriginLab Corp.</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>Single Mode FC/APC Fiber Optic Patch Cables</td>
			<td>ThorLabs Inc.</td>
			<td>P3-460B-FC</td>
			<td></td>
		</tr>
		<tr>
			<td>10X Olympus Plan Achromat Objective</td>
			<td>ThorLabs Inc.</td>
			<td>RMS10X</td>
			<td>RMS10X - 10X Olympus Plan Achromat Objective, 0.25 NA, 10.6 mm WD&#160;</td>
		</tr>
	</tbody>
</table>

scanning light scattering profiler (slps) based methodology to quantitatively evaluate forward and backward light scattering from intraocular lenses

The scanning light scattering profiler (SLSP) methodology has been developed for the full-angle quantitative evaluation of forward and backward light scattering from intraocular lenses (IOLs) using goniophotometer principles. This protocol describes the SLSP platform and how it employs a 360&#176; rotational photodetector sensor that is scanned around an IOL sample while recording the intensity and location of scattered light as it passes through the IOL medium. The SLSP platform can be used to predict, non-clinically, the propensity for current and novel IOL designs and materials to induce light scatter. Non-clinical evaluation of light scattering properties of IOLs can significantly reduce the number of patient complaints related to unwanted glare, glistening, optical defects, poor image quality, and other phenomena associated with the unintended light scattering. Future studies should be conducted to correlate SLSP data with clinical results to help identify which measured light scatter is most problematic for patients that have undergone cataract surgery subsequent to IOL implantation.

Goniophotometry measurements can produce 360&#730;R of signal when the sensor is not located on the plane of the light source. However, to collect measurements from scattered light on the plane of the light source (0&#730;I) the sensor will need to eclipse the light source, resulting in less than 360&#730;R of signal. In our experiments, it was determined that ~20&#730;R of signal was blocked as the sensor eclipsed the light source.
<p class="jove_content" fo:keep-together.within-page...

Watch this Scientific Journal Video about Scanning Light Scattering Profiler SLPS Based Methodology to Quantitatively Evaluate Forward and Backward Light Scattering from Intraocular Lenses at JoVE.com

Scanning Light Scattering Profiler SLPS Based Methodology to Quantitatively Evaluate Forward and Backward Light Scattering from Intraocular Lenses

This protocol describes the scanning light scattering profiler (SLSP) that enables the full-angle quantitative evaluation of forward and backward scattering of light from intraocular lenses (IOLs) using goniophotometer principles.

Scanning Light Scattering Profiler (SLPS) Based Methodology to Quantitatively Evaluate Forward and Backward Light Scattering from Intraocular Lenses

The scanning light scattering profiler (SLSP) methodology has been developed for the full-angle quantitative evaluation of forward and backward light ...

scanning-light-scattering-profiler-slps-based-methodology-to

Universidad de Cartagena UDEC

Research

JoVE Journal

Engineering

7.5K Views.  U.S. Food and Drug Administration. This protocol describes the scanning light scattering profiler (SLSP) that enables the full-angle quantitative evaluation of forward and backward scattering of light from intraocular lenses (IOLs) using goniophotometer principles.

Video: Scanning Light Scattering Profiler SLPS Based Methodology to Quantitatively Evaluate Forward and Backward Light Scattering from Intraocular Lenses

Measuring Spatially- and Directionally-varying Light Scattering from Biological Material

Light interacts with an organism's integument on a variety of spatial scales. For example in an iridescent bird: nano-scale structures produce color; the milli-scale structure of barbs and barbules largely determines the directional pattern of reflected light; and through the macro-scale spatial structure of overlapping, curved feathers, these directional effects create the visual texture. Milli-scale and macro-scale effects determine where on the organism's body, and from what viewpoints and under what illumination, the iridescent colors are seen. Thus, the highly directional flash of brilliant color from the iridescent throat of a hummingbird is inadequately explained by its nano-scale structure alone and questions remain. From a given observation point, which milli-scale elements of the feather are oriented to reflect strongly? Do some species produce broader "windows" for observation of iridescence than others? These and similar questions may be asked about any organisms that have evolved a particular surface appearance for signaling, camouflage, or other reasons.
In order to study the directional patterns of light scattering from feathers, and their relationship to the bird's milli-scale morphology, we developed a protocol for measuring light scattered from biological materials using many high-resolution photographs taken with varying illumination and viewing directions. Since we measure scattered light as a function of direction, we can observe the characteristic features in the directional distribution of light scattered from that particular feather, and because barbs and barbules are resolved in our images, we can clearly attribute the directional features to these different milli-scale structures. Keeping the specimen intact preserves the gross-scale scattering behavior seen in nature. The method described here presents a generalized protocol for analyzing spatially- and directionally-varying light scattering from complex biological materials at multiple structural scales.

We present a non-destructive method for sampling spatial variation in the direction of light scattered from structurally complex materials. By keeping the material intact, we preserve gross-scale scattering behavior, while concurrently capturing fine-scale directional contributions with high-resolution imaging. Results are visualized in software at biologically-relevant positions and scales.

Light interacts with an organism's integument on a variety of spatial scales. For example in an iridescent bird: nano-scale structures produce color; the ...

Using Neutron Spin Echo Resolved Grazing Incidence Scattering to Investigate Organic Solar Cell Materials

The spin echo resolved grazing incidence scattering (SERGIS) technique has been used to probe the length-scales associated with irregularly shaped crystallites. Neutrons are passed through two well defined regions of magnetic field; one before and one after the sample. The two magnetic field regions have opposite polarity and are tuned such that neutrons travelling through both regions, without being perturbed, will undergo the same number of precessions in opposing directions. In this case the neutron precession in the second arm is said to &#34;echo&#34; the first, and the original polarization of the beam is preserved. If the neutron interacts with a sample and scatters elastically the path through the second arm is not the same as the first and the original polarization is not recovered. Depolarization of the neutron beam is a highly sensitive probe at very small angles (&#60;50&#160;&#956;rad) but still allows a high intensity, divergent beam to be used. The decrease in polarization of the beam reflected from the sample as compared to that from the reference sample can be directly related to structure within the sample.
In comparison to scattering observed in neutron reflection measurements the SERGIS signals are often weak and are unlikely to be observed if the in-plane structures within the sample under investigation are dilute, disordered, small in size and polydisperse or the neutron scattering contrast is low. Therefore, good results will most likely be obtained using the SERGIS technique if the sample being measured consist of thin films on a flat substrate and contain scattering features that contains a high density of moderately sized features (30 nm to 5 &#181;m) which scatter neutrons strongly or the features are arranged on a lattice. An advantage of the SERGIS technique is that it can probe structures in the plane of the sample.

Progress has been made in utilizing spin echo resolved grazing incidence scattering (SERGIS) as a neutron scattering technique to probe the length-scales in irregular samples. Crystallites of [6,6]-phenyl-C61-butyric acid methyl ester have been probed using the SERGIS technique and the results confirmed by optical and atomic force microscopy.

The spin echo resolved grazing incidence scattering (SERGIS) technique has been used to probe the length-scales associated with irregularly shaped ...

Failure Analysis of Batteries Using Synchrotron-based Hard X-ray Microtomography

Imaging morphological changes that occur during the lifetime of rechargeable batteries is necessary to understand how these devices fail. Since the advent of lithium-ion batteries, researchers have known that the lithium metal anode has the highest theoretical energy density of any anode material. However, rechargeable batteries containing a lithium metal anode are not widely used in consumer products because the growth of lithium dendrites from the anode upon charging of the battery causes premature cell failure by short circuit. Lithium dendrites can also form in commercial lithium-ion batteries with graphite anodes if they are improperly charged. We demonstrate that lithium dendrite growth can be studied using synchrotron-based hard X-ray microtomography. This non-destructive imaging technique allows researchers to study the growth of lithium dendrites, in addition to other morphological changes inside batteries, and subsequently develop methods to extend battery life.

Synchrotron-based hard X-ray microtomography is used to image the electrochemical growth of dendrites from a lithium metal electrode through a solid polymer electrolyte membrane.

Imaging morphological changes that occur during the lifetime of rechargeable batteries is necessary to understand how these devices fail. Since the advent ...

Measurement of Scattering Nonlinearities from a Single Plasmonic Nanoparticle

Plasmonics, which are based on the collective oscillation of electrons due to light excitation, involve strongly enhanced local electric fields and thus have potential applications in nonlinear optics, which requires extraordinary optical intensity. One of the most studied nonlinearities in plasmonics is nonlinear absorption, including saturation and reverse saturation behaviors. Although scattering and absorption in nanoparticles are closely correlated by the Mie theory, there has been no report of nonlinearities in plasmonic scattering until very recently. 
Last year, not only saturation, but also reverse saturation of scattering in an isolated plasmonic particle was demonstrated for the first time. The results showed that saturable scattering exhibits clear wavelength dependence, which seems to be directly linked to the localized surface plasmon resonance (LSPR). Combined with the intensity-dependent measurements, the results suggest the possibility of a common mechanism underlying the nonlinear behaviors of scattering and absorption. These nonlinearities of scattering from a single gold nanosphere (GNS) are widely applicable, including in super-resolution microscopy and optical switches. 
In this paper, it is described in detail how to measure nonlinearity of scattering in a single GNP and how to employ the super-resolution technique to enhance the optical imaging resolution based on saturable scattering. This discovery features the first super-resolution microscopy based on nonlinear scattering, which is a novel non-bleaching contrast method that can achieve a resolution as low as l/8 and will potentially be useful in biomedicine and material studies.

Saturable and reverse saturable scattering were discovered in isolated plasmonic particles and adopted as a novel non-bleaching contrast method in super-resolution microscopy. Here the experimental procedures of detecting and extracting nonlinear scattering are explained in detail, as well as how to enhance resolution with the aid of saturated excitation microscopy.

Plasmonics, which are based on the collective oscillation of electrons due to light excitation, involve strongly enhanced local electric fields and thus ...

Stimulated Stokes and Antistokes Raman Scattering in Microspherical Whispering Gallery Mode Resonators

Dielectric microspheres can confine light and sound for a length of time through high quality factor whispering gallery modes (WGM). Glass microspheres can be thought as a store of energy with a huge variety of applications: compact laser sources, highly sensitive biochemical sensors and nonlinear phenomena. A protocol for the fabrication of both the microspheres and coupling system is given. The couplers described here are tapered fibers. Efficient generation of nonlinear phenomena related to third order optical non-linear susceptibility &#935;(3) interactions in triply resonant silica microspheres is presented in this paper. The interactions here reported are: Stimulated Raman Scattering (SRS), and four wave mixing processes comprising Stimulated Anti-stokes Raman Scattering (SARS). A proof of the cavity-enhanced phenomenon is given by the lack of correlation among the pump, signal and idler: a resonant mode has to exist in order to obtain the pair of signal and idler. In the case of hyperparametric oscillations (four wave mixing and stimulated anti-stokes Raman scattering), the modes must fulfill the energy and momentum conservation and, last but not least, have a good spatial overlap.

Efficient generation of nonlinear phenomena related to third order optical non-linear susceptibility &#935;(3) interactions in triply resonant silica microspheres is presented in this paper. The interactions here reported are: Stimulated Raman Scattering (SRS), and four wave mixing processes comprising Stimulated Anti-stokes Raman Scattering (SARS).

Dielectric microspheres can confine light and sound for a length of time through high quality factor whispering gallery modes (WGM). Glass microspheres ...

Fabrication of White Light-emitting Electrochemical Cells with Stable Emission from Exciplexes

The authors present an approach for fabricating stable white light emission from polymer light-emitting electrochemical cells (PLECs) having an active layer which consists of blue-fluorescent poly(9,9-di-n-dodecylfluorenyl-2,7-diyl) (PFD) and &#960;-conjugated triphenylamine molecules. This white light emission originates from exciplexes formed between PFD and amines in electronically excited states. A device containing PFD, 4,4&#39;,4&#39;&#39;-tris[2-naphthyl(phenyl)amino]triphenylamine (2-TNATA), Poly(ethylene oxide) and K2CF3SO3 showed white light emission with Commission internationale de l&#39;&#233;clairage (CIE) coordinates of (0.33, 0.43) and a Color Rendering Index (CRI) of Ra = 73 at an applied voltage of 3.5 V. Constant voltage measurements showed that the CIE coordinates of (0.27, 0.37), Ra of 67, and the emission color observed immediately after application of a voltage of 5 V were nearly unchanged and stable after 300 sec.

The authors present a method for fabricating stable white-light-emitting electrochemical cells utilizing emission from exciplexes formed between a blue-emitting fluorene polymer and aromatic amines.

The authors present an approach for fabricating stable white light emission from polymer light-emitting electrochemical cells (PLECs) having an active ...

Synchrotron X-ray Microdiffraction and Fluorescence Imaging of Mineral and Rock Samples

In this report, we describe a detailed procedure for acquiring and processing&#160;x-ray microfluorescence (&#956;XRF), and Laue and powder microdiffraction two-dimensional (2D) maps at beamline 12.3.2 of the Advanced Light Source (ALS), Lawrence Berkeley National Laboratory. Measurements can be performed on any sample that is less than 10 cm x 10 cm x 5 cm, with a flat exposed surface. The experimental geometry is calibrated using standard materials (elemental standards for XRF, and crystalline samples such as Si, quartz, or Al2O3 for diffraction). Samples are aligned to the focal point of the x-ray microbeam, and raster scans are performed, where each pixel of a map corresponds to one measurement, e.g., one XRF spectrum or one diffraction pattern. The data are then processed using the in-house developed software XMAS, which outputs text files, where each row corresponds to a pixel position. Representative data from moissanite and an olive snail shell are presented to demonstrate data quality, collection, and analysis strategies.

We describe a beamline setup meant to carry out rapid two-dimensional x-ray fluorescence and x-ray microdiffraction mapping of single crystal or powder samples using either Laue (polychromatic radiation) or powder (monochromatic radiation) diffraction. The resulting maps give information about strain, orientation, phase distribution, and plastic deformation.

In this report, we describe a detailed procedure for acquiring and processing&#160;x-ray microfluorescence (&#956;XRF), and Laue and powder ...

Label-Free Imaging of Single Proteins Secreted from Living Cells via iSCAT Microscopy

We demonstrate interferometric scattering (iSCAT) microscopy, a method capable of detecting single unlabeled proteins secreted from individual living cells in real time. In this protocol, we cover the fundamental steps to realize an iSCAT microscope and complement it with additional imaging channels to monitor the viability of a cell under study. Following this, we use the method for real-time detection of single proteins as they are secreted from a living cell which we demonstrate with an immortalized B-cell line (Laz388). Necessary steps concerning the preparation of microscope and sample as well as the analysis of the recorded data are discussed. The video protocol demonstrates that iSCAT microscopy offers a straightforward method to study secretion at the single-molecule level.

We present a protocol for the real-time optical detection of single unlabeled proteins as they are secreted from living cells. This is based on interferometric scattering (iSCAT) microscopy, which can be applied to a variety of different biological systems and configurations.

We demonstrate interferometric scattering (iSCAT) microscopy, a method capable of detecting single unlabeled proteins secreted from individual living ...

O-cresol Concentration Online Measurement Based On Near Infrared Spectroscopy Via Partial Least Square Regression

Unlike macroscopic process variables, near-infrared spectroscopy provides process information at the molecular level and can significantly improve the prediction of the components in industrial processes. The ability to record spectra for solid and liquid samples without any pretreatment is advantageous and the method is widely used. However, the disadvantages of analyzing high-dimensional near-infrared spectral data include information redundancy and multicollinearity of the spectral data. Thus, we propose to use partial least squares regression method, which has traditionally been used to reduce the data dimensionality and eliminate the collinearity between the original features. We implement the method for predicting the o-cresol concentration during the production of polyphenylene ether. The proposed approach offers the following advantages over component regression prediction methods: 1) partial least squares regression solves the multicollinearity problem of the independent variables and effectively avoids overfitting, which occurs in a regression analysis due to the high correlation between the independent variables; 2) the use of the near-infrared spectra results in high accuracy because it is a non-destructive and non-polluting method to obtain information at microscopic and molecular scales.

The protocol describes a method of predicting o-cresol concentration during the production of polyphenylene ether using near-infrared spectroscopy and partial least squares regression. To describe the process more clearly and completely, an example of predicting the o-cresol concentration during the production of polyphenylene is used to clarify the steps.

Unlike macroscopic process variables, near-infrared spectroscopy provides process information at the molecular level and can significantly improve the ...

Scattering And Absorption of Light in Planetary Regoliths

Theoretical, numerical, and experimental methods are presented for multiple scattering of light in macroscopic discrete random media of densely-packed microscopic particles. The theoretical and numerical methods constitute a framework of Radiative Transfer with Reciprocal Transactions (R2T2). The R2T2 framework entails Monte Carlo order-of-scattering tracing of interactions in the frequency space, assuming that the fundamental scatterers and absorbers are wavelength-scale volume elements composed of large numbers of randomly distributed particles. The discrete random media are fully packed with the volume elements. For spherical and nonspherical particles, the interactions within the volume elements are computed exactly using the Superposition T-Matrix Method (STMM) and the Volume Integral Equation Method (VIEM), respectively. For both particle types, the interactions between different volume elements are computed exactly using the STMM. As the tracing takes place within the discrete random media, incoherent electromagnetic fields are utilized, that is, the coherent field of the volume elements is removed from the interactions. The experimental methods are based on acoustic levitation of the samples for non-contact, non-destructive scattering measurements. The levitation entails full ultrasonic control of the sample position and orientation, that is, six degrees of freedom. The light source is a laser-driven white-light source with a monochromator and polarizer. The detector is a mini-photomultiplier tube on a rotating wheel, equipped with polarizers. The R2T2 is validated using measurements for a mm-scale spherical sample of densely-packed spherical silica particles. After validation, the methods are applied to interpret astronomical observations for asteroid (4) Vesta and comet 67P/Churyumov-Gerasimenko (Figure 1) recently visited by the NASA Dawn mission and the ESA Rosetta mission, respectively.

Numerical and experimental methods are presented for multiple scattering of light in discrete random media of densely-packed particles. The methods are utilized to interpret the observations of asteroid (4) Vesta and comet 67P/Churyumov-Gerasimenko.

Theoretical, numerical, and experimental methods are presented for multiple scattering of light in macroscopic discrete random media of densely-packed ...